Suggestions for an amp

It has been suggested that I should look at a different amp to get the best sound out of my speakers. 
I have a Yamaha Aventage RX-A830. Front speakers are Monitor Audio Silver 8. 
I am mostly interested in something to provide the best sound while listening to music but also be decent for HT. I have an Orbit with a Grado Black 1 cartridge for vinyl. 
I am not looking at spending a ton of money and will definitely consider used (I am looking at several on this site). 
Many thanks!